1. Field of the Invention
The invention relates to a load suspension device that can be braced horizontally with hydraulics. The load suspension device that can be adjusted, locked, and braced horizontally, via hydraulics, can be used with container spreaders that must be adjusted and locked. However, the area of use is not limited to these load suspension devices, but rather includes situations wherever hydraulic work elements or load suspension devices must be adjusted, locked, and braced.
2. The Prior Art
Freight containers are handled with special load suspension devices, such as spreaders. Since there are different, raster-type lengths of these freight containers, it is necessary for the load suspension device to be able to adapt to this changed length.
Usually, this is done in so-called telescope spreaders, which are constructed so that the spreader can change the distance between its load suspension points—the twist locks—in the raster lengths of the containers.
This is achieved by providing two extension bars disposed in the longitudinal container axis, in opposite directions, that run in a base frame that hangs on the support device, in a horizontally displaceable manner, and are locked in the base frame in a position corresponding to the container length, with shape fit.
For this purpose, each extension bar is horizontally displaced by a hydraulic cylinder, and brought into position. This is accomplished by applying oil pressure to one of the work spaces, depending on the desired direction of movement, and when the desired telescope position is reached, the pressure is shut off.
The aforementioned locking device consists, for each extension bar, of a bolt that is disposed perpendicular to the longitudinal container axis, hydraulically activated, and biased with a spring, which bolt drops into a lock on the extension bar in the pressure-free state, and thus locks the extension device in the desired position.
Usually, the bolt is pulled out of the lock in the pressurized state, using the hydraulic cylinder. Thus, the extension bar is released for a horizontal movement.
Because of the gate closure, the system must be viewed as very rigid; in the case of collisions of the extension bar with standing containers or other obstacles in the handling facility, great forces act on the extension bar, and these can lead to destruction of the locking device.
Also, the unavoidable play in the lock in the event of horizontal movements of the work machine brings about acceleration forces and braking forces and impacts on the spreader and on the load suspension. This leads to great stress on all of the modules involved, particularly in the case of a load suspension device as it is usual in straddle carriers, for example. Finally, the locking device, as an independent module, also requires its own control, and this results in indirect costs, along with the direct costs for the module.
German Patent Application No. DE 29 40 117 A1 describes a spreader arrangement consisting of a base section and at least one section that can be moved in and out by a piston/cylinder unit. The spreader arrangement has a hydraulic circuit with a reservoir and a source for a hydraulic pressure medium as well as lines, which connect the reservoir and the source with the piston/cylinder unit and with a solenoid valve disposed in the lines. Furthermore, there is an electrical control circuit for the solenoid valve, having a power source, solenoids for activation of the solenoid valve, a selection switch that can be manually activated, for optional excitation of one of the solenoids, and holding means for maintaining the excitation of a solenoid when the selection switch is moved back into a neutral position, and for preventing simultaneous excitation of both solenoids. Furthermore, a position control device for shutting off one of the solenoids is provided, once the extendable section reaches a predetermined location with reference to the base section. In the system, all mechanical locking devices in the form of pins or the like, for locking the individual sections in place relative to one another once a predetermined position has been reached, are eliminated. The document furthermore shows an electrical and hydraulic control system with which the spreader sections can be precisely adjusted to the different container lengths. The control system can be switched to the different containers, having numerous different lengths, with only minimal modification.
German Patent Application No. DE 44 27 891 C1 describes a pressure-medium-activated gripper for stones that must be aligned, conveyed, and set down, by layers, whereby multiple pressure-medium drives work one after the other in a time sequence. At least two pressure-medium drives that work one after the other are connected with a common pressure-medium circuit, and the pressure-medium drive that works first is connected, on the pressure side, with a valve that responds to a predetermined response pressure, which valve switches the work pressure to a pressure-medium drive that works subsequently.
German Patent Application No. DE 195 03 866 C1 describes a spreader for four-point suspension of containers equipped with corner fittings, which spreader has a hydraulic device with which the spreader can be adjusted. A locking possibility for the hydraulic device or for the spreader is not described.
German Patent Application No. DE 600 20 371 C1 describes a container handling device consisting of a spreader having two telescoping forks, which are displaceable relative to one another. Adjustment of the spreader takes place with cables, but these are not biased.
These previous devices have several disadvantages, including: shape-fit locking devices, higher costs due to wear, and damage due to impact of the extension bar with obstacles, all of which result in failure of the load suspension device and shut-down times. Furthermore, as a result of impact stress, a transfer to the work machine, for example the lift or industrial truck, comes about.